Not to make things more confusing, but I have the same enlarger and head, and I find the Dichroic filters can be a bit short on maximum contrast. My serrendipitous solution was to get an old set of dupont or kodak under the lens filters, with bakelite screw on the lens holder. The number 5 there gives a contrastier result.
On the assumption your dichroic filtes act as perfect filters, doubling up on the same filter will only let the same image developing wavelengths pass twice, but will make it harder for your eyes to see the image on the easil.